None of the above helped me completely. Although Oventoaster made me think. I had a couple of adb on my system. Removed them almost all.
I am running android studio on ubuntu 14.04 64 bit.
So I checked manually /home/xxxxx/Android/Sdk/platform-tools/adb
where xxxxx was my linux username
this gave
/home/xxxxx/Android/Sdk/platform-tools/adb: error while loading shared libraries: libstdc++.so.6: cannot open shared object file: No such file or directory
https://stackoverflow.com/a/27415749/4453157
solved it for me.